JPS5842233B2 - Two-stage fluidized coal gasification method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-stage fluidized gasification method that improves the gasification efficiency, increases the processing capacity, and improves the operability of the gasifier and gas purification. It is something.

For a coal gasification method to be put into practical use by converting coal into a fluid and utilizing it, the process must be economical and the gasifier and gas purification must have good operability.

In order to improve the economic efficiency of the process, (a) carbon utilization efficiency is high; (b) processing capacity per unit hearth area is large (/→ highly effective use of gasifying agent (especially expensive steam) In addition, in order to ensure good operability of the gasifier and gas purification process, clinker should not be generated in the lower gasifier, and the crude gas should not contain any substances that would interfere with the purification process. It is necessary that there be no.

The inventor investigated and established a two-stage fluidized gasification method that satisfies these conditions.

That is, to explain the present invention in detail, (1) The factor that reduces carbon utilization efficiency is (a) unreacted carbon in the solid matter discharged outside the cool (0) system produced during the carbonization process of coal. We focused our efforts on eliminating these as much as possible.

In the case of slightly caking coal and non-caking coal, which are the raw materials for the fluidized gasification method, tar is approximately 10 to 15 φ thicker than the coal, and in addition to being discharged outside the system, it also absorbs mainly H2 produced in the lower stage gasifier. This significantly reduces carbon use efficiency.

Therefore, in order to improve carbon utilization efficiency, it is necessary to thermally decompose and gasify tar in the upper stage gasifier.

Furthermore, in order to reduce the amount of unreacted carbon in the solid matter, it is necessary to expand the gasification reaction area in the gasification device and further promote the gasification reaction.

For this purpose, oxygen-containing gas is blown into the upper stage gasifier, the furnace temperature is set to 800°C or higher and 9500°C or lower, and the generated cool is thermally decomposed. Allow gas reaction to occur.

(2) Processing capacity per unit hearth area is due to carbon consumption in the gasifier due to decrease in char yield due to high temperature of the upper gasifier, partial combustion of fine coal and char, promotion of water gas reaction, etc. Increase by increasing the amount.

(3) The utilization efficiency of the gasifying agent (% water vapor) is improved by making the upper gasifier the water gasification reaction area.

(4) What impedes the operability of the gasifier is the formation of clinker in the lower gasifier.

Factors for clinker formation include flow state and temperature.

When tar is present in the upper gasifier, the tar absorbs the hydrogen produced in the lower gasifier, so the lower gasifier suppresses the water gas reaction and is under conditions that promote the producer gas reaction, i.e., high temperature. (950°C or higher).

However, when tar is decomposed in the upper stage, this phenomenon disappears, so the lower stage is heated to a temperature of 800°C, where the water gas reaction takes place mainly.
It is now possible to operate at ~950°C, reducing the possibility of clinker formation and improving operability.

If tar is present in the crude gas, it becomes liquid in the temperature drop section and precipitates in the purification equipment, impeding its functionality and operability. However, by thermally decomposing and gasifying the tar in the upper gasifier This phenomenon is eliminated and purification performance and operability are improved.

As mentioned above, the fluidized bed furnace is combined into two stages, and clinker is produced by blowing oxygen-containing gas into the upper stage at a temperature corresponding to the properties of the raw coal (SOO~9500G), and at the lower stage at a temperature of 850°C or higher. If the coal is operated at a temperature below 100%, coal can be gasified efficiently, stably, and continuously.

The upper limit of these temperature conditions is set at a range in which no clinker is generated in both the upper and lower stages, and the lower limit is set at a range in which tar decomposition is sufficient in the upper stage, and a range in which the reaction of the produced gas is sufficiently promoted in the lower stage. It is what was done.

By doing this, it is possible to maintain the inside of each furnace at the desired temperature without causing a high temperature area higher than the melting point of the ash to appear in either the upper or lower tier, achieving the above-mentioned intended purpose. We were able to achieve this.

The method of the present invention will now be explained in detail with reference to the accompanying drawings.

The drawing shows one embodiment of the method of the invention.

In the drawings, A is a gasifier, B is a cyclone, and C is a char storage tank.

The gasifier A is an upper fluidized fluidized furnace 1 with a slot-shaped lower part.
and a lower fluidized fluidized furnace 2 provided with a gasifying agent distribution plate 4 are connected by a conduit 3 having a limited cross-sectional area.

The upper fluidized bed furnace 1 is provided with an overflow pipe 5 for discharging powdered char having a relatively large particle size, and the lower fluidized bed furnace 2 is provided with an overflow pipe 6 and an ash discharge pipe 7 in the center of the dispersion plate. .

This gasifier has an O to 3 depending on the purpose of use of the generated gas.
It is operated at a pressure of 0 kg/cyf.

Dry and particle size-adjusted raw material coal is introduced into the upper fluidized bed furnace 1, and heated to a temperature of 800°C to 950° C. by the combustion heat generated by the hot gas rising from the lower fluidized bed furnace 2 through the conduit 3 and the oxygen-containing gas injected into the upper fluidized bed furnace 1. A fluidized process is carried out at a temperature below °C to carbonize the coal and at the same time thermally decompose the generated tar to produce char.

The upper fluidized bed temperature is controlled by adjusting the amount of oxygen-containing gas supplied.

Of the generated char, relatively large particles are discharged from the overflow pipe 5, and the fine particles of char that left the fluidized bed furnace together with the generated gas are separated by a cyclone B, and both are received in a char storage tank C, where they are transferred to the lower stage. It is supplied to the upper part of the distribution plate 4 of the fluidized fluidized furnace 2.

The gas from which the fine char has been separated by the cyclone B is degassed and then processed according to the purpose of use and used for the intended purpose.

The char supplied to the lower fluidized fluidized furnace 2 is brought into a fluidized state by a mixed gas of a predetermined amount of oxygen-containing gas and water vapor fed through the distribution plate 4, and at the same time gasification of oxidation, water gas, generator gas, etc. A reaction occurs, the gas is gasified, and the gas rises to the upper fluidized bed furnace 1.

The fluidized bed temperature of the lower gasifier 2 is a temperature favorable for water gas reaction, that is, 850° C. or more and 950° C. or less, and the temperature is controlled mainly by steam.

The upper and lower fluidized bed temperatures are selected depending on the properties of the raw coal.

The ash produced as a result of the gasification reaction is discharged through the overflow pipe 6 and the discharge pipe 7 in the center of the distribution plate.

The technical and economical effects brought about by employing such means in the present invention are as described above.

Next, examples of the present invention will be shown.

Example lower stage fluidized furnace inner diameter 3607IL to height 15001n1L,
Using a gasifier with the structure shown in the attached diagram, which has an upper stage fluidized bed furnace with an inner diameter of 300n and a height of 41,501m, Pacific coal whose particle size was adjusted to an average particle size of 1.5mm was heated at 9/ever in the gas specific pressure cuff. The results of tests on the effects of air injection in the upper gasifier on gasification efficiency, coal throughput, steam utilization efficiency, etc. are shown in the attached table.

The above results prove that the objectives of the present invention, such as increasing the amount of coal processed, increasing the amount of gas generated, and improving the gasification efficiency and steam utilization rate, have been achieved.

[Brief explanation of the drawing]

The attached drawings are schematic diagrams showing an example of an apparatus for explaining the present invention in detail, in which A is a gasifier, B is a cyclone, C is a char storage tank, 1 is an upper fluidized fluidized furnace, 2 is a lower fluidized fluidized furnace, and 3 is a conduit, 4 is a dispersion plate, 5 is a char overflow pipe, 6 is an ash overflow pipe, 7
8 is an ash discharge pipe, 8 is an oxygen-containing gas inlet, and 9 is an oxygen-containing gas + steam inlet.

Claims (1)

[Claims] 1 Using a fluidized furnace divided into two stages, upper and lower, in the upper stage, volatile components of coal are gasified with hot gas from the lower stage to produce char, and the char is separated from the gas and supplied to the lower stage, In the lower stage, in the two-stage fluidized gasification method, oxygen-containing gas and water vapor are introduced from the bottom to perform a gasification reaction. Oxygen-containing gas is blown into the upper fluidized bed, and the fine particles of coal and char in the furnace are and burn a part of the combustible gas to raise the furnace temperature from soo'c to 950°C,
A two-stage fluidized coal gasification method characterized in that the lower stage is operated at a temperature of 850° C. or higher and a temperature at which no clinker is produced.